Gas-oil-water separation system and process

Abstract

An improved system and method of gas and petroleum production from locations such as offshore facilities in which oily water and/or wet oil or an oil/water mixture is fed to a Podbielniak type centrifugal liquid/liquid contactor for separation and purification of the oil and water phases.

We claim: 
     
       1. In a gas/oil/water separation system comprising a high pressure first stage separator where gas and a first liquid are separated from a feed mixture of gas, oil and water, a medium-pressure second stage separator for receiving the first liquid which contains a reduced portion of gas and for separating additional gas from the liquid, a low-pressure third stage separator for receiving a second liquid from the second stage separator and separating additional gas from the second liquid, the improvement comprising: a first centrifugal countercurrent liquid/liquid contacting device arranged and positioned to receive a water rich third liquid containing free oil from the third stage separator for removal of an effective amount of the free oil to produce purified water.   
     
     
       2. The system of claim 1 further comprising: a second centrifugal countercurrent liquid/liquid contacting device arranged and positioned to process a fourth oil rich liquid containing free water from the third stage separator and to remove an effective amount of free water and to produce dewatered oil.   
     
     
       3. An improved gas/oil/water separation system comprising a first stage separator for removing a first portion of gas from a mixture of gas, oil and water, a second stage separator arranged to separate a second portion of gas from liquid effluent from the first stage separator, a third stag separator arranged to separate a third portion of gas from liquid effluent from the second stage separator, the improvement comprising: a centrifugal countercurrent liquid/liquid contacting device positioned to receive a liquid effluent containing an oil/water mixture from the third stage separator and arranged to produce dewatered oil and purified water from the liquid effluent.   
     
     
       4. An improved gas/oil/water separation system comprising a first stage separator for removing a first portion of gas from a mixture of gas, oil and water, a second stage separator arranged to separate a second portion of gas from liquid effluent from the first stage separator, a third stage separator arranged to separate a third portion of gas from liquid effluent from the second stage separator the improvement comprising: a high capacity centrifugal countercurrent liquid/liquid contacting device arranged and positioned to receive an oil rich liquid containing free water from the third stage separator and to remove an effective amount of free water and to produce dewatered oil from the oil rich liquid.   
     
     
       5. The system according to any of claims 1-4 wherein the centrifugal countercurrent liquid/liquid contacting device is a Podbielniak liquid/liquid contacting device. 
     
     
       6. The system according to claim 1 further comprising: a pump positioned and arranged to receive the third liquid and to discharge the third liquid, and a device for removing particulate matter wherein both the pump and the device are arranged and positioned upstream of the inlet of the centrifugal countercurrent liquid/liquid contacting device.   
     
     
       7. The system of claim 2 further comprising: a pump and a filter positioned to receive the fourth liquid from the third stage separator and to discharge the filtered fourth liquid to the second centrifugal countercurrent liquid/liquid contacting device.   
     
     
       8. The system of claim 3 further comprising: a pump and a filter positioned to receive the liquid effluent from the third stage separator and to discharge the filtered liquid effluent to the centrifugal countercurrent liquid/liquid contacting device.   
     
     
       9. The system of claim 4 further comprising: a pump and a filter positioned to receive the oil rich liquid from the third stage separator and to discharge the filtered oil rich liquid to the centrifugal countercurrent liquid/liquid contacting device.   
     
     
       10. The system according to any of claims 1-4 wherein the system is on a fixed offshore gas production facility. 
     
     
       11. The system according to any of claims 1-4 wherein the system is on a fixed offshore petroleum production facility. 
     
     
       12. The system according to any of claims 1-4 wherein the system is on a floating offshore gas production facility. 
     
     
       13. The system according to any of claims 1-4 wherein the system is on a floating offshore floating petroleum production facility. 
     
     
       14. An offshore gas, oil and water separation system comprising: a first stage separator for receiving a first feed mixture of gas, oil and water at about 8400 kPa and for discharging a first portion of separated gas and a first portion of unseparated gas, oil and water;   a second stage separator for receiving as a feed the first portion of unseparated gas, oil and water at about 2400-2800 kPa from the first stage separator and for discharging a second portion of separated gas and a second portion of unseparated gas, oil and water;   a third stage separator for receiving as a feed the second portion of unseparated gas, oil and water from the second stage separator and for discharging a mixture of oily water containing about 2,000 to 5,000 ppmv free oil and wet oil containing up to about 40% by weight water; and   a first centrifugal countercurrent liquid/liquid contacting device for receiving as a feed the oily water from the third stage separator and for producing acceptably oil-free water.   
     
     
       15. The system of claim 14 further comprising: a second centrifugal countercurrent liquid/liquid contacting device for receiving as a feed the wet oil from the third stage separator and for producing acceptably water-free oil.   
     
     
       16. An offshore gas, oil and water separation system comprising: a first stage separator having a liquid and gas discharge;   a second stage separator having a liquid and gas discharge; and   a third stage separator having a liquid and gas discharge wherein the liquid discharge from the third stage separator is supplied to a single Podbielniak centrifugal countercurrent liquid/liquid contacting means for producing substantially purified water and substantially purified oil.   
     
     
       17. An improved method of recovering oil and removing water in a gas/oil/water separation process having a plurality of separations of gas from a liquid mixture of gas, oil and water and wherein effluents from the last separation of gas from the liquid include an oil rich effluent and a water rich effluent wherein the improvement comprises: dewatering the oil rich effluent.from the last separation containing up to 50 percent by weight of free water by feeding the effluent oil to a centrifugal countercurrent liquid/liquid contacting device arranged and positioned to receive and dewater said oil rich effluent of an effective amount of the free water and   producing dewatered oil.   
     
     
       18. An improved method of recovering water and removing oil in a gas/oil/water separation process having a plurality of separations of gas from a liquid mixture of gas, oil and water wherein effluents from the last separation of gas from the liquid include an oil rich effluent and a water rich effluent wherein the improvement comprises: deoiling the water rich effluent from the last separation containing up to 50 percent by weight of free oil by feeding the water rich effluent to a first centrifugal countercurrent liquid/liquid contacting device arranged and positioned to receive and deoil said water rich effluent of an effective amount of the free oil and   producting substantially deoiled water.   
     
     
       19. An improved method of recovering oil and water in a gas/oil/water separation process having a plurality of separations of gas from a liquid mixture of gas, oil and water wherein a liquid effluent containing oil and water is produced from the last separation in the plurality of separations wherein the improvement comprises: feeding the liquid effluent from the last separation to a single certrifugal countercurrent liquid/liquid contacting device arranged and positioned to receive the liquid effluent and   producing dewatered oil and purified water from the liquid effluent.